Signaling system



ly 1 1939- v G. N. SAUL 2.166536 SIGNALING SYSTEM" 7 Filed March 26, 1956 MARC/NA L FIG. 2

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T /3 usurp I l d- E E INVIENTOR G. N. SAUL B) ATTORNEY Patented July 18, 1939 UNITED STATES PATENT OFFICE SIGNALING sYsTEM George N. Saul, Brooklyn, N. Y., assignor to Bell Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of'New York Application March 26, 1936, Serial No. 71,056

1 Claim.

This invention relates to signaling systems wherein electric circuits are controlled by an interrupter and more particularly to means associated with an interrupter alarm circuit to cause 5 I an alarm to be given and an emergency arrangement brought into service to control the electric circuits upon the occurrence of an abnormal or being" released or being steadily energized, the.

2'0 alarm will be operated and the emergency equipment will be brought into service. Y

It has been experienced in systems of such a type, that the associated circuits in which relaysv associated with the interrupter lead or conductor are located, frequently Suffer an appreciable tential drop over the battery supply leads between the circuits and the power supply fuses. These leads are usually longer in length, hence higher v in-resistance, than the battery supply lead to the alt-alarm control relay and usually carry a larger. current with the result that the I. R. drop to the connected circuits is usually greater than that to the alarm control relay and in practice may reach a maximum of 1.5 Volts. Under such a condition 35 it has been found that the control relay will hold operated during the open period of the interrupter and bring in an alarm falsely. The false operation of the alarm has also been caused by induc tive' surges to which the alarm relay is subject and 4 which are caused by the interruption of circuits positive manner to: indicate unstandard or ab-' normal circuit conditions and which is immune as to thoseconditions-which heretofore were instrumental in causing the" alarm to be actuated falsely.

The invention will be readily understood from the following detailed description made with refererice to the accompanying drawing in which 5' Fig. 1 is a diagrammatic representation of a" circuit embodying the present invention;

Fig. 2 is a schematic illustration of the circuit condition which prevailed prior to the present invention; and

Fig. 3 is a schematic illustration of the circuit of Fig. 2'modified to'include the features 'of this invention. 7

An interrupter I, constantly rotatingcreates a stream of periodic impulses in the conductor 2, 15'

herein identified as the signal interrupter circuit or interrupter lead. These impulses flow through the'back' contact'and armature of relay'3 to conduct/or 4 herein identified as the distributing circuit. The distributing circuit is connected through the armatures' and back contacts of a plurality of relays 5, 6 and l to a plurality of'occasioria'lly energized circuits, such as 8, 9, I0 and Il'.

The interrupterci'rcuit 2 is connected to the winding of a polarized relay [3, the other terminal of the winding of relay I'Bbeing connected to battery 14 byway of resistance element 16. A high resistance l! is connected to ground and is in shunt with the winding of relay [3 when interrupter l is in such a position as to connect grouridto the relay winding. Relay [3 is poled in such a direction as to respond to interruptions effected by the interrupter l and its armature follows such interruptions. If the impulses supplied by the interrupter are at the rate of 40, 60 or 120 interruptions per minute; then the armature of relay 13 will be moved between its front and back contacts at the rate of 40, 60 or 120 times per minute. v 40 During the periods that the armature of relay I3 is resting on its front contact, a circuit is closed for relay I9 andthis relay, being slow to release, will in general maintain its armature in its operated position as long as relay I3 is constantly operating, as described.

In the same manner, when the armature of relay l3 is resting on its back contact, a relay 20 is energized and this relay also being slow to re- 0 V tain its armature operated even though relays I9 and 20 should release momentarily.

The conditions above described are normal and will be maintained as long as interrupter I operates properly and the circuit 2 maintained in a standard condition.

Let it now be assumed that conductor 2 becomes opened near the interrupter I or at any place between the interrupter I and relay l3; then relay I3 will cease to operate and its armature will rest steadily on its back contact. Under this condition relay 20 will be maintained energized but relay I9 will become deenergized and. after a short interval of time will release its armature. The circuit for relay 2| is opened accordingly and this relay will allow its armature to return to normal.

It will now be pointed out that relay 2| will also be released when the conductor 2 becomes grounded. In such a case, relay I3 will become steadily operated and its armature will rest on its front contact continually. Under these conditions relay I9 will be maintained energized and relay 20 will become deenergized and after a short interval of time release its armature and cause relay 2| to restore to normal.

The grounding of conductor 2 may take place either on the conductor 2 itself, on the distributing circuit 4 or on any one of the circuits such as 8,9,|0or||,etc.

It should be noted that in the case where one of the circuits such as 8 is grounded, this ground will be communicated to all other circuits such as 9, I0 and II and the associated apparatus of such circuits will be rendered inoperative.

It will thus be seen that when the interrupter circuit 2 is opened between the interrupter I and relay I3, or such circuit is grounded, relay 2| will restore to normal. 7

Upon the restoration to normal of relay 2|, a circuit is established from ground, armature and back contact of relay 2|, winding of relay 22 to battery. 7 Relay 22 operates in this circuit and locks in a circuit extending from ground, normal contacts of key 23, front contact and inner left-hand armature of relay 22, winding of relay 22 to battery. Through the operation of its outer left-hand armature, relay 22 closes a circuit extending from ground, outer left-hand armature of the alarm 24. At the same time a 'circuit is terrupter circuit 2, alarm 24 is sounded and the distributing circuit 4 is permanently grounded.

At the same time, the ground for operating relay 22 is communicated to the visual signal 25 which is lighted steadily. 7

Through its inner right-hand armature, relay 22 places a ground on conductor 26 which finds a circuit through relay 21 and. resistance 28 to battery whereupon relay 2'I becomesoperated. Upon the operation of relay 21, a short circuit about the winding of relay29 is opened and this relay now becomes operated in series with resistance 30. In like manner, upon the operation of relay 29, a short circuit about the winding of relay 3| is opened and this relay in turn becomes operated in series with resistance 32. Relay 3|,

and front contact of relay 22 to battery by way' in operating, nowcloses a short circuit about the winding of relay 21 and after a short interval of time this relay releases its armature. When relay 2'! restores, it in turn short-circuits relay 29 and relay 29 in turn short-circuits relay 3|. This cycle of operations occurs periodically.

Upon the first operation of relay 3 a circuit is closed from ground, outer right-hand armature and front contact of relay 3 I, left-hand armature and back contact of relay 33, winding of relay 34, left-hand winding of relay 33 to battery. Relay 34 operates in this circuit but relay 33, being mar- .'ginal, fails to operate. Upon the operation of relay 34, a circuit to the right-hand winding of relay 33 is closed, but this only results in shortcircuiting such winding, since a ground is to be found on conductor 26 which is communicated through the armature and front contact of relay 34 to oneside of the right-hand winding of relay 33, the other side being grounded through the outer right-hand armature of relay 3 Upon the following release of relay 3 I, the short circuit about the right-hand winding of relay 33 is removed and relay 33 now operates in a circuit from ground, middle right-hand armature and front contact of relay 22, conductor 26, armature and front contact of relay 34, right-hand winding of relay 33, winding of relay 34, left-hand winding of relay 33 to battery. Relay 33 now operates its armatures and prepares a circuit wherein relay 34 Will become deenergized. As soon as relay 3| again becomes operated a ground is connected directly to the left-hand winding of relay 33, and the winding of relay 34 and the right-hand winding of relay 33, in series therewith are short-circuited. Relay 34 becomes deenergized and relay 33 holds operated.

Upon the next deenergization of relay 3|, relay 33 releases.

Thus it will be seen that for each two complete cycles of operation of relay 3|, relay 33 will go through one complete cycle of operations.

Upon each energization of relay 33; a circuit is closed for relay 35, which relay operates and places a ground on conductor 36 which is communicated in parallel to each of the relays 5, 6 and I and to the signal lamp 31. The design and adjustment of relays 21, 29 and 3| are such that the rate of operation of relay 35 is the same asv the rate of interrupter I.

Since the distributing circuit 4 is permanently grounded at the front contact of relay 3, each of the circuits 8, 9, III and II, etc. will be grounded during the deenergization of relays 5, 6 and 'I with the result that the circuits are intermittently grounded as before.

It should be noted. that even though a particular circuit such as 8 becomes permanently grounded, this ground. cannot be communicated to the other signaling circuits during the operation of the emergency interrupter comprising re-' If, however, the trouble is of a more permanent nature, then the actuation-of key 23 does not result in the restoration of the circuit to normal.

The alarm 24 and the visual signals 25 and 31 will remain operated and the trouble will have to be traced to its source and corrected. When the trouble is cleared, the circuit may be restored to normal by a momentary actuation of key 23.

In previous systems of this nature, relay i3 was a sensitive neutral relay and the battery supply lead 4| (see Fig. 2) to this relay was connected directly to battery H! by way of the busbar 53, that is, no resistances i3 and H were associated therewith.

The previous system of this type is illustrated in the schematic shown in Fig. 2. The connected or work circuits with which this interrupter circuit functions may include relays or any other type of equipment which may be actuated by the interrupted ground from interrupter or directly to steady ground. In any event, the connected circuits as well as the control relay l3 receive current from the same supply battery |4. For purposes of illustration only, Fig. 2 shows a relay which operates from battery I4, by way of bus 52, battery supply lead 53 (herein indicated as a resistance), winding of relay 5|, back contact and upper armature of relay 5, armature and back contact of relay 3 to interrupted ground at the interrupter l. The relay 5| may be utilized to control the flashing of a lamp such as 15. Relay 55 is shown to illustrate other apparatus in the circuit of which relay 5| is a part, which draws its current from battery M by way of bus-bar 52 and supply lead 53. Due to the relative locations of the alarm relay l3 and the equipment such as relays 5| and 55, the battery supply lead 53 to the latter will frequently be of greater length and, therefore, of greater resistance than the battery supply lead 4| to the alarm relay l3. It will also be noted that due to the extensive equipment served by the lead 53, this lead will carry current in excess of that carried by lead 5|. Under these conditions the potential drop to the connected circuits, that is, over the battery supply lead 53, is greater than that to the alarm relay l3 over battery supply lead 4|.

Due to the fact that the potential drop between the bus-bar 5|] and relay l3 by way of battery supply lead 4| is less than the drop between bus 52 and the connected circuit indicated by the point 56, by way of the battery supply lead 53, there exists a difference of potential across the winding of relay l3 when the interrupter is on open circuit, which is of sufiicient magnitude to hold relay l3 operated when it should be released. This difference of potential causes current to traverse a path from battery It, bus-bar 50, battery supply lead 4|, winding of relay |3, back contact and armature of relay 3, upper armature and back contact of relay 5, windings of relays 5| and 55 to ground. It is to be understood that relays 5|, 55 and lamp l5 and their circuit connections have been chosen merely to illustrate some of many conditions which may exist and to more clearly identify the condition which causes the relatively high potential drop over the battery supply lead 53; Actually there is more equipment, such as relays 55, 5|, etc., which is supplied by the battery 14 by way of the supply lead 53.

The current traversing the path traced in the preceding paragraph is sufficient to hold operated the sensitive neutral relay l3 of Fig, 2. Such an untimely operation of relay l3 results in a false operation of the alarm circuit.

To overcome this dificulty, the present invention provides for the introduction of an artificial potential drop in the supply lead to relay l-3 which is equal to or greater than the known drop over the supply lead 53 to the connected circuits, and utilizes a polarized relay I3 in place of the neutral relay I-3 of Fig. 2. This condition is illustrated in Fig. 3.

The artificial potential drop is effected by in cluding a resistance It in series between the'polarized relay l3 and bus-bar 5|) and a relatively high resistance IT in shunt with relay |3 to ground, the shunt eifect prevailing only when the interrupter is on a grounded segment. Under this condition, that is when interrupter I is on a grounded segment, the polarized relay |3 operates in a circuit extending from battery l4, bus-bar 50, resistance l6, winding of relay Hi to ground at the interrupter. When the interrupter is on an ungrounded segment current from the battery traverses resistances I6 and l! to ground creating a potential drop over resistance It to relay l3. Since the maximum potential drop over the supply lead 53 is known, the values of the resistances l6 and I! are selected so as to effect a potential drop over resistance It when the interrupter is on an ungrounded segment, which is equal to or greater than the maximum known drop over the lead 53.

It will now be noted that with a potential drop over resistance It to relay l3 equal to or greater than that over the'supply lead 53 of a connected circuit there will either be no potential difference across the winding of relay l3 when the interrupter is on open circuit, or it will be of such a nature as to cause the flow of current through relay l3 in a direction such as to aid its release, if operated. The arrow shown on relay l3 (Fig. 3) indicates the direction of flow of current in the relay necessary to cause its operation. Due to the fact that the drop over resistance I5 is now equal to or greater than that over lead 53 there will either be no flow of current in the lead 8 or it will be in the direction indicated by the arrow associated therewith which is opposed to the direction necessary to effect the operation of relay l3. The result attained is that polarized relay I3 will always release its armature whenever the interrupter lead is ungrounded.

The arrangement just described also prevents the false operation of the alarm relay on inductive surges which result from the opening of a circuit such as 8, for example, which may include an inductively wound relay such as relay 5 I. Such surges will be in a direction opposite to the direction of the normal operating current for polarized relay 3 and hence such surges will not cause this relay to falsely operate during the open period of the interrupter as they did with the neutral relay I3 in Fig. 2 which was caused to occasionally respond under this condition after a reversal of its flux.

What is claimed is:

In combination, a grounded load circuit including a load having one terminal grounded, a source of current having one terminal grounded and a supply lead of appreciable resistance interconnecting the ungrounded terminal of said load and the ungrounded terminal of said source of current, said load drawing a known maximum current from said source and producing a known maximum potential drop over said supply lead, a polarized relay, a second supply lead interconnecting one terminal of said relay and the ungrounded terminal of said source of current, means connecting the second terminal of said relay to the ungrounded terminal of said load,

and interrupter, means connecting said interrupter between the said second terminal of said relay and ground, a resistance, means connecting said resistance between the first-mentioned ter-- supply lead greater than the known maximum potential drop over said first battery lead whereby current flows through said relay in the nonoperate direction when said interrupter removes ground potential from said second terminal of 5 said relay.

GEORGE N. SAUL. 

